depends upon where you live, the electricity supply at my previous home never damaged anything, after shifting to my new home(about half km away) chargers don't last a month (counterparts of same chargers survived 6-7 years in my old home some were left plugged in for months even), wapda has changed transformer 6th time in 2 months. (we have supply from two different feeders, ups and generator so impact of no electricity for 22-40 hours each time wasn't felt).